Etazolate (EHT-0202) is a selective, positive GABAA receptor modulator has completed phase II clinical trials in patients with Alzheimer's disease. It is also a selective phosphodiesterase-4 inhibitor that is specific for cAMP. Etazolate showed anxiolytic and antidepressant activity and could be useful in managing post-traumatic stress disorder.

ADX-71149 (JNJ-40411813), a phenylpiperidine-substituted pyridone, is positive allosteric modulator (PAM) metabotropic glutamate type 2 (mGlu2) receptor activity. In fed rats, JNJ-40411813 was rapidly absorbed with an absolute oral bioavailability of 31%. ADX-71149 (JNJ-40411813) demonstrates antipsychotic activity in vivo rodents experiments. ADX-71149 (JNJ-40411813) is being jointly developed by Addex Therapeutics and Janssen Pharmaceuticals, a Johnson & Johnson company, for the treatment of epilepsy. Addex Therapeutics was also developing the candidate for schizophrenia, major depressive disorder and anxiety disorders. However, development in these indications has been discontinued.

LY2300559 is a dual metabotropic glutamate receptor 2 (mGluR2) positive allosteric modulator and cysteinyl leukotriene receptor 1 (CysLTR1) antagonist. Eli Lilly was developing LY2300559 for the prevention of migraine. LY2300559 development has been discontinued.

Dexmecamylamine (TC-5214, also known, as S isomer of mecamylamine) is a positive allosteric modulator of α4β2 neuronal nicotinic receptors, rather than an open-channel blocker. It was evaluated as a potential adjunct treatment for patients with major depressive disorder (MDD). TC-5214 was generally well tolerated, however, the studies were not supportive of an antidepressant effect for TC-5214 in patients with MDD and inadequate response to prior antidepressant therapy. The Phase 2b clinical trial of TC-5214 for the treatment for overactive bladder (OAB) revealed the high dose of TC-5214 demonstrated mixed results on the co-primary endpoints by providing a statistically significant reduction in micturition frequency and an improvement that did not reach statistical significance on episodes of urinary incontinence. As a consequence of these results, this drug was discontinuing further development of TC-5214 in OAB. The study for using TC-5214 in patients with refractory hypertension was also terminated.

Dihydromyricetin is a flavonoid component from the Ampelopsis species japonica, megalophylla, and grossedentata; Cercidiphyllum japonicum; Hovenia dulcis; Rhododendron cinnabarinum; some Pinus species; and some Cedrus species, as well as Salix sachalinensis. Dihydromyricetin exerts a more rapid antidepressant-like effect than does a typical antidepressant, in association with enhancement of BDNF expression and inhibition of neuroinflammation. Dihydromyricetin inhibited the proliferative potential of fibroblasts in the lung cancer cells through targeting the activation of Erk1/2 and Akt. Therefore, there is scope for dihydromyricetin to be evaluated further for the treatment of lung cancer. Dihydromyricetin supplementation improves glucose and lipid metabolism as well as various biochemical parameters in patients with nonalcoholic fatty liver disease, and the therapeutic effects of dihydromyricetin are likely attributable to improved insulin resistance and decreases in the serum levels of tumor necrosis factor-alpha, cytokeratin-18, and fibroblast growth factor 21.

AVL-3288 is a type I selective positive allosteric modulator of α7 nACHRs. It represents a "first-in-class" drug for the treatment of cognitive deficits in CNS disorders such as schizophrenia and potentially other diseases of cognitive impairment such as Alzheimer’s disease and ADHD. AVL-3288 was successfully tested in representative animal models of cognitive dysfunction in schizophrenia, a disease where α7 nAChR function is impaired. To date, no specific treatments for cognitive deficits in schizophrenia exist and approved therapies do not satisfactorily improve cognition. AVL-3288 is currently in human phase I trials.

Lorediplon is a novel non-benzodiazepine, the hypnotic drug acting as a GABAA receptor modulator, differentially active at the alpha1-subunit, associated with promoting sleep. As compared with other selective benzodiazepine receptor agonists, lorediplon has demonstrated in pre-clinical studies a potent hypnotic profile with potential advantages in sleep maintenance and sleep architecture preservation associated with a good safety profile, that is, no induction of tolerance, lack of next-day hangover effect, weak effect on muscular tone, and weak interaction with ethanol. Lorediplon demonstrated a minimum of 10-fold and the 6-fold increase in potency (respectively) in the spontaneous motor activation studies, compared with the currently marketed hypnotics (zolpidem and zaleplon). Additionally, when the electroencephalogram (EEG) effects of lorediplon and zolpidem were compared in the sleep-wake cycle in the mouse, lorediplon demonstrated a 10-fold increase in potency compared with zolpidem in the sleep-wake cycle and 13% greater possibility of fewer wake episodes than zolpidem. At concentrations of 1.2mg/kg, lorediplon demonstrated a 57%increased effect on Slow Wave Sleep (SWS), when compared with a placebo. In clinical trials, the clinical safety and tolerability were excellent for all doses tested. In pharmacokinetic studies, after oral administration, lorediplon is rapidly absorbed from the gastrointestinal tract reaching maximum plasma concentrations at approximately 2 h. Lorediplon demonstrated a dose-dependent improvement in sleep, whereas zolpidem showed a more sustained wake after sleep onset effect. No next-day hangover effects were observed. These sleep effects are also consistent with the pharmacokinetic profile of lorediplon.

MPEP (2-methyl-6-(phenylethynyl)pyridine) was one of the first compounds found to act a selective antagonist for the metabotropic glutamate receptor subtype mGluR5. It was under development by Novartis in the late 1990's. MPEP was found to produce neuroprotective effects following acute brain injury in animals. MPEP was also found to have positive effects on animal models of depression, anxiety and morphine withdrawl.